Depression is one of the most common of the mental illnesses, having morbidity rate of over 10% in the general population. Depression is characterized by feelings of intense sadness, despair, mental slowing, loss of concentration, pessimistic worry, agitation, and self-deprecation (Harrison's Principles of Internal Medicine 2490–2497 (Fauci et al. eds., 14th ed. 1998)). Depression can have physical manifestations including insomnia, hypersomnia, anorexia, weight loss, overeating, decreased energy, decreased libido, and disruption of normal circadian rhythms of activity, body temperature, and endosine functions. In fact, as many as 10% to 15% of depressed individuals display suicidal behavior. R. J. Baldessarini, Drugs and the Treatment of Psychiatric Disorders: Depression and Mania, in Goodman and Gilman's The Pharmacological Basis of Therapeutics 431 (9th ed. 1996).
U.S. Pat. No. 4,435,419 to Epstein et al. discloses racemic, (±)-1-(3,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane for use as an anti-depressant agent.
Administration of a racemic, i.e., 50:50, mixture of the (+)- and the (−)-enantiomer of any drug, for example (±)-1-(3,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane, to a patient can be disadvantageous. First, the racemic mixture might be less pharmacologically active than one of its enantiomers, rendering racemic drugs inherently inefficient. Second, the racemic mixture may be more toxic to a patient than one of its enantiomers, so that administration of a racemic mixture can lead to undesirable side effects in a patient.
Accordingly, there is a clear need in the art for an enantiomer of (±)-1-(3,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane, the enantiomer being preferably substantially free of the corresponding opposite enantiomer, which would overcome one or both of the aforementioned disadvantages.
Citation of identification of any reference in Section 2 of this application is not to be construed as an admission that such reference is prior art to the present application.